This invention relates to eyeglass frames. More particularly, this invention relates to eyeglass frames designed for ready insertion and removal of lenses.
It is well known that many people have visual problems which require them to wear corrective lenses in order to see properly. Commonly, such lenses are mounted in a pair of eyeglass frames comprising a pair of lens rims joined to each other, usually via a bridge portion, which are placed upon the nose of the wearer. A temple piece which extends backward over the wearer's ears, is provided at the outer edge of each rim.
Continuing changes in a person's vision necessitate periodic reexaminations of their eyes and usually purchase of new corrective lenses. In many instances the old eyeglass frames are still servicable, but because of the difficulty of removing the old lenses and installing the new, new eyeglass frames are purchased instead.
In addition to the purely utilitarian function of holding a pair of corrective lenses, eyeglass frames also serve an ornamental function. Eyeglass frames are, in fact, a form of jewelry. Some persons have gone so far as to have a different pair of eyeglasses to match different outfits of clothing. This practice, however, is wasteful because a separate set of expensive corrective lenses ordinarily is purchased for each pair of frames, due to the difficulty of removing and replacing the lenses from most eyeglass frames.
Attempts have been made in the prior art to provide eyeglass frames with split rims to facilitate removal and insertion of lenses. Examples are Talobre U.S. Pat. No. 2,473,619; Amaru U.S. Pat. No. 3,589,802 and Livas U.S. Pat. No. 3,762,804. Such prior designs have not been completely satisfactory either because special tools such as tiny jeweler's screwdrivers, have been required to open the frames for insertion or removal of a lens or because the lenses have not been mounted in the frames securely enough to prevent them from falling out at inopportune moments.
Others in the prior art have attempted to provide readily removable and replaceable temple pieces. Such patents include Spill U.S. Pat. No. 2,210,507; Rosenheim U.S. Pat. No. 2,379,928; Rosenheim U.S. Pat. No. 2,504,157; Eloranta U.S. Pat. No. 2,671,379; Dunbar U.S. Pat. No. 3,744,887 and Manufacture Oyonnaxienne French Pat. No. 1,037,166. Such devices are subject to the disadvantge that in many instances the removable temple pieces exhibit an undesirable tendency to separate from the frames, particularly when the glasses are not in use and are folded in the closed position.
Yet another disadvantage of many prior art glasses' frames is the tendency of such frames to fall off particularly when the wearer tips his head forward to look down at something. In some instances, the glasses may even be lost, for example when the wearer is looking down from an elevated position or from above a body of water. To combat this problem, a safety strap is sometimes positioned around the back of the head or neck of the wearer with the ends of the strap secured to the temple pieces of the eyeglass frames. Such safety straps are, however, unwieldy and inconvenient. Others have attempted to overcome this problem by designing the eyeglass frames so that the temple pieces exert a pressure against the head of the wearer. Such devices include those disclosed in Pyle U.S. Pat. No. 347,738; Nelson U.S. Pat. No. 2,608,905; Amundsen U.S. Pat. No. 3,001,200; Chartrice U.S. Pat. No. 3,395,964 and Lyons U.S. Pat. No. 3,654,376.
A further disadvantage of prior art glasses frames involves the use of tiny, precision hinges, called findings, which materially add to the difficulty and expense of manufacturing the frames.